897results about How to "Reduce phase noise" patented technology

Frequency standards based on mode-locked fiber lasers, fiber amplifiers and fiber-based ultra-broad bandwidth light sources, and applications of the same.

A novel time-to-digital converter (TDC) used as a phase/frequency detector and charge pump replacement in an all-digital PLL within a digital radio processor. The TDC core is based on a pseudo-differential digital architecture making it insensitive to NMOS and PMOS transistor mismatches. The time conversion resolution is equal to an inverter propagation delay, e.g., 20 ps, which is the finest logic-level regenerative timing in CMOS. The TDC is self calibrating with the estimation accuracy better than 1%. The TDC circuit can also serve as a CMOS process strength estimator for analog circuits in large SoC dies. The circuit also employs power management circuitry to reduce power consumption to a very low level.

MEMS-based, computer system, clock generation and oscillator circuits and LC-tank apparatus for use therein are provided and which are fabricated using a CMOS-compatible process. A micromachined inductor (L) and a pair of varactors (C) are developed in metal layers on a silicon substrate to realize the high quality factor LC-tank apparatus. This micromachined LC-tank apparatus is incorporated with CMOS transistor circuitry in order to realize a digital, tunable, low phase jitter, and low power clock, or time base, for synchronous integrated circuits. The synthesized clock signal can be divided down with digital circuitry from several GHz to tens of MHz—a systemic approach that substantially improves stability as compared to the state of the art. Advanced circuit design techniques have been utilized to minimize power consumption and mitigate transistor flicker noise upconversion, thus enhancing clock stability.

A low noise multi-loop radio frequency synthesizer is disclosed for the read channel in a hard disk drive, and for RF wireless communications local oscillator applications. The frequency synthesizer receives an input reference signal having a frequency fR, into a fine tune phase locked loop and into a coarse tune phase locked loop. Driven by the input reference signal, the fine tune PLL outputs a fine tune signal with a frequency fR.P, where P is an integer, while the coarse tune PLL, also driven by the same input reference signal, outputs a coarse tune signal with a frequency fR.A, where A is an integer. A translation phase locked loop has a unity multiplication factor and is driven by the fine tune signal output. The frequency synthesizer finally has a Gilbert cell double balanced mixer coupled between the coarse tune and the translation phase locked loops, wherein the Gilbert cell mixer combines the coarse tune signal and the output signal of the translation phase locked loop and couples the mixed signal into the translation phase locked loop. The translation loop outputs a signal with a frequency which is proportional to the linear sum of the coarse tune signal and the fine tune signal.

A multi-band receiver in which characteristics including a tracking error are improved is provided with a variable frequency oscillator circuit, a variable divider circuit (39) for dividing an oscillation signal (SVCO) of the variable frequency oscillator circuit, and mixer circuits (15I) and (15Q) for subjecting a received signal SRX to frequency conversion into an intermediate frequency signal (SIF) by a local oscillation signal (SLO). A divided output of the variable divider circuit (39) is supplied as the local oscillation signal (SLO) to each of the mixer circuits (15I) and (15Q). When a signal in a first frequency band is received, the division ratio n of the variable divider circuit (39) and the oscillation frequency of the variable frequency oscillator are changed to change the reception frequency in the first frequency band. When a signal in a second frequency band is received, at least the oscillation frequency of the variable frequency oscillator circuit is changed to change the reception frequency in the second frequency band.

In a method and a device for carrying frequency synthesis, in particular in a distance measuring device based on the principle of evaluating the change over time in the phase of an electromagnetic radiation emitted by a radiation source and remitted by an object aimed at, a frequency, which is preferably furnished by a quartz oscillator, is regulated in a ring oscillator with N delay elements (V₁, V₂, V₃, . . . , V_N) to a desired first high frequency (F), which is used as a mixer frequency or as a modulation frequency. The signals at the N delay elements (V₁, V₂, V₃, . . . , V_N) are delivered to a multiplexer, which is switched over with a cadence that is equivalent to 2*N times the frequency of the low-frequency measurement signal to be evaluated to produce a modulation frequency or mixer frequency.

Exemplary embodiments of the invention provide a system, method and apparatus for spread spectrum functionality for a free-running, reference harmonic oscillator. In an exemplary embodiment, an apparatus comprises a reference oscillator adapted to provide a reference signal having a reference frequency; and a spread spectrum controller adapted to control the reference oscillator to generate a spread-spectrum reference signal at a plurality of different reference frequencies during a predetermined or selected time period. An exemplary apparatus may also include a coefficient register adapted to store a plurality of coefficients and a plurality of controlled reactance modules responsive to a corresponding coefficient of the plurality of coefficients to modify an amount of reactance effectively coupled to the reference oscillator. An exemplary spread spectrum controller is further adapted to sequentially modify the plurality of coefficients during the predetermined time period to provide the spread spectrum reference signal.

The present invention provides a method for reducing phase noise in OFDM systems by analyzing a time-dependent representation of the phase noise that changes in real time according to received data. The analysis of real time signals is based on processing statistical properties of phase noise and received data. The statistical properties of phase noise are represented by a covariance matrix R_ψψ. The basis of the multiplicative phase noise decomposition which represents the varying in time phase noise component, is selected from the eigenvectors of R_ψψ. The present invention suggests replacing the fixed representation of the phase noise as suggested by prior art with a system and time-dependent representation that changes in real time according to received data. The method according to the present invention is implemented within An OFDM transceiver.

A micromachined air-cavity resonator, a method for fabricating the micromachined air-cavity resonator, and a band-pass filter and an oscillator using the same are provided. In particular, a micromachined air-cavity resonator including a current probe fabricated together when the air-cavity resonator is fabricated, and a groove structure for rejecting detuning effect when an external circuit of a package substrate is coupled to the current probe, a millimeter-wave band-pass filter using the same, and a millimeter-wave oscillator using the same are provided. The micromachined air-cavity resonator includes a cavity structure which comprises a current probe simultaneously formed through a fabrication process, and a groove structure; and a package substrate integrated with the cavity structure. Thus, the micromachined air-cavity resonator can be easily fabricated by etching a silicon substrate and easily integrated to the package substrate using the flip-chip bonding.

A clock recovery circuit through NFC active load modulation based on a digital phase-locked loop is formed by a digital phase-locked loop and a digital delay locking loop. The digital phase-locked loop works under a tracking carrier frequency mode and a fixed oscillation frequency mode. Under the fixed oscillation frequency mode, oscillation frequency is formed and locked in the period of tracking a carrier wave, the digital phase-locked loop is an all-digital structure phase-locked loop, and the digital delay locking loop receives a split phase clock of the phase-locked loop, and fast locks a clock which is closest to a carrier phase through comparison with a phase of the carrier wave. The digital delay locking loop works under a phase tracking mode and a fixed phase mode, under the fixed phase mode, the digital delay locking loop constantly outputs the same split phase clock, and the clock is obtained under a tracking mode. The clock recovery circuit reduces frequency difference caused by injecting noise in the time of conversion from a closed loop to an open loop, enables bandwidth of the phase-locked loop to be reduced to further lower phase noise, and can avoid the situation that the phase difference cannot be corrected due to the fact that the bandwidth is reduced.

A symmetrical stacked inductor comprising a plurality of conductive layers using at least one conductive line formed out of a symmetrical and geometric conductive layer and having at least one inter-metal dielectric layer for isolating each conductive layer, and wherein the conductive line does not intersect; and a plurality of vias placed between the inter-metal dielectric layers for electrical conduction.

The invention belongs to the field of microwave photonics, and discloses a system and method for frequency tunable microwave phase shifting. The method comprises the following steps that after a continuous light carrier is splitted, one beam of the continuous light carrier is processed by a MZ Mach-zehnder, and double-sideband optical signals restrained by the carrier are produced; the other beam of the continuous light carrier is processed by a phase modulator, and phase-shifted light carrier signals are produced; two beams of light signals are combined in a wave mode, one one-step sideband is removed through a tunable micro-ring filter in a filtering mode, a frequency-moved carrier signal and a phase-shifted carrier signal are obtained, photovoltaic conversion is carried out through a photoelectric detector, and a phase shift microwave electrical signal is produced; the resonant frequency of the tunable micro-ring filter is equal to any one-step sideband of the two one-step sidebands output by the MZ Mach-zehnder by changing the frequency of an input voltage drive signal and the resonant wavelength of the tunable micro-ring filter, and the frequency of the phase shift microwave signal is changed. The system and method for the frequency tunable microwave phase shifting is stable in output performance, fast in phase shift adjusting response, small in output microwave range fluctuation and continuously adjustable in wide frequency range.

The present invention relates to a calibrated phase-locked loop (PLL), which has a calibration mode for measuring a tuning gain of a variable frequency oscillator (VFO) and a PLL mode for normal operation. Calibration information based on the tuning gain is used during the PLL mode to regulate a PLL loop gain. During the calibration mode, the calibrated PLL operates as a frequency-locked loop (FLL) for low frequency lock times, and during the PLL mode the calibrated PLL operates as a PLL for high frequency accuracy and low noise. By regulating the PLL loop gain, the desired noise spectrum and dynamic behavior of the PLL may be maintained in spite of variations in the operating characteristics or in the characteristics of the PLL components.